My dad was a computer programmer all the way back in the late 60s/early 70s. He actually worked with Bill Gates years before Microsoft was conceived. My parent's basement is something of a computer
graveyard museum and they actually have one computer down there my dad built from a Heathkit kit back in the 60s. You 'program' it using a bank of switches on its front and, after it performs the computation, a series of little lightbulbs read out the answer (in binary, so you have to know that to understand it). IIRC, it adds, subtracts, mutliplies, and divides. Which was pretty cool back then. Of course, since one had to know binary to figure out what 2+2 equaled, one suspects it had very little practical value